With the spread of information and communication technologies, various image (video) contents are provided in various forms.
On the other hand, display devices capable of displaying a high resolution video (image) such as full high vision are spread, and thus, there is much opportunity to display various image (video) contents on the display device. For example, there is much opportunity to display low resolution image (video) contents having a resolution of horizontal 640 pixels and vertical 360 pixels on a high resolution display device corresponding to a full high vision standard of horizontal 1920 pixels and vertical 1080 pixels. In the high resolution display device, 1920 pixels×1080 pixels image (video) can be displayed by performing an upscale process of an embedded scaler on an image (video) having a resolution lower than the display resolution. However, if a low-resolution image (video) is displayed as a high resolution image by the upscale process, in some cases, jaggies occur in the edge portion.
In addition, in the high resolution display device, in a case where a compressed image (video) is decoded to be displayed, in some cases, mosquito noise occurs in the edge portion.
If a sharpening process (for example, a sharpness emphasis process or an enhancement process) is performed on the image, jaggies or mosquito noise are overemphasized in the edge portion, so that there is a problem in that image quality is deteriorated. If a sharpening process disclosed in, for example, Patent Literature 1 (JP 2003-348379 A) is performed on an image like the above-described image, a feeling of detail of a texture portion can be improved, but jaggies or mosquito noise of an edge portion are overemphasized, so that the jaggies or mosquito noise are noticeable in the edge portion.
Since the jaggies or noises occurring in the edge portion become obstruction, it is preferable that the jaggies or noises are reduced.
Techniques for reducing the jaggies or noises occurring in the edge portion have been developed. For example, Patent Literature 2 (JP 2004-336652 A) discloses a technique of reducing mosquito noise without destructing detail of a significant texture portion by identifying a pixel of interest based on an edge detection signal, a smoothened signal, and an edge signal and performing a filtering process based on identification information indicating a result of the identification and the edge signal.